Force RGB mode in Mac OS X to fix the picture quality of an external monitor

I recently bought a MacBook Pro (with ‘Retina’ screen), but when I hooked it up to my Dell U2410 monitor via HDMI cable I was shocked by the poor picture quality. The contrast was all wrong and text was misshapen. No amount of calibration in the monitor or software would fix it.

Short answer: OS X thinks my monitor is a TV, and is using the YCbCr colour space rather than RGB. I had to override an EDID setting to force the RGB colour space, and it is now working correctly.

Long answer: I haven’t owned a Mac for a while and had forgotten how difficult much of the “Apple community” can be when it comes to anything that can’t be adjusted in System Preferences. Googling for problems with external monitors on MacBooks found dozens of threads on official and unofficial Apple forums, all full of people with the same problem. The most common response was to blame the monitor, despite assurances from the stricken users that the monitor worked beautifully in Linux and Windows, even on the same machine under Boot Camp.

“You just haven’t calibrated it!”, “You are just too used to Retina now!”, “You just need to buy a Thunderbolt display!” Apple people also like to solve problems by throwing more money at it. (I realise that owning a Mac makes me an Apple person, too. Hypocritical self-loather?)

My lucky break was reading that the current colour space was “YCbCr” when I was browsing the monitor’s settings menu. I was sure that it was using RGB when hooked up to my PC, so I started searching instead for forcing RGB mode in OS X. It didn’t appear to be available out-of-the-box, but I have had some experience in overriding EDID settings for similar purposes so I searched instead for that.

I found this thread on the forums. Mr Schwarz, thanks very much. Your thread and script was incredibly helpful and informative. It was written to fix problems connecting an external monitor via DisplayPort, but it fixed my HDMI issue just the same. I’ve summarised the required steps below.

My last word is to wonder what Apple is playing at. It seems that this problem has been reported by a lot of people for a long time, and I expect it would require a fairly simple software update. Do they just not care about those using third-party components, or are they actively attempting to force people on to Thunderbolt displays?

How to force RGB in Mac OS X

These steps have been updated for Mac OS version 10.11, “El Capitan”. See below for differences for previous versions of the system.

  1. Download the patch-edid.rb script from the forums thread above, or download Andrew Daugherity’s improved patch-edid.rb script from his github page. Put the script in your home directory.
  2. Disable “rootless” mode, you can follow these instructions: How to modify System Integrity Protection in El Capitan.
  3. Reboot.
  4. Connect only the external monitor(s) in question, if you can (I closed my MacBook lid, for example). The script will make override files for any connected monitor.
  5. Type “ruby patch-edid.rb” in Terminal.
  6. A new folder will be created in your home directory. Move it into the “/System/Library/Displays/Contents/Resources/Overrides” folder. You may have to create the Resources and Overrides folders. If Finder tells you that you are overwriting an existing folder, consider backing it up first.
  7. Restart your computer. The picture quality should be fixed from this point.
  8. Re-enable “rootless” mode, the instructions are available on the same guide: How to modify System Integrity Protection in El Capitan.
  9. Reboot. Enjoy your monitor.

To undo the changes, either delete the folder you had copied to the Overrides folder (if it didn’t already exist) or replace it with the folder you had backed up. You will need to re-enable rootless mode to do this.

Earlier versions of Mac OS X

The process is a little more straightforward. There are two differences to the steps above:

  1. You do not need to disable/re-enable rootless mode and perform the subsequent reboots.
  2. The overrides folder location is “/System/Library/Displays/Overrides”.


I no longer own a Macbook Pro, but if you’re having trouble with any of these steps, please have a look through the comments below (and note that there are multiple pages). Many questions have been answered with helpful tips from others.

Update, 20 Nov 2016: In the comments Marcus has proposed a faster method that doesn’t require SIP to be disabled. If people have success with this I’ll update this post.

Update, 8 Feb 2016: A comment from nos1609 below, warns about a bootloop that can occur when running other patches (like the pixel-clock patch) simultaneously, and how to get around it.

Update, 23 Nov 2015: According to Peter’s post, you don’t need to disable SIP if you use recovery mode. If others have similar success with this method I’ll update the process.

Update, 3 Oct 2015: I have amended this post to target El Capitan. I have taken the steps from bigmcguire’s process, posted in the comments. Although some are still having issues, it appears to be working for people. Thanks!

Update, 29 May 2015: Mac OS 10.11 El Capitan does things a little differently. You must first disable the new ‘rootless’ mode and then use a different overrides folder: /System/Library/Displays/Contents/Resources/Overrides. Rootless can then be re-enabled if desired, as confirmed by nos1609 in the comments below. El Capitan is still in beta, I’ll update this post if the issue is still apparent afterwards.

Update, 26 May 2014: If you have had trouble with limited resolutions being available after the fix, check out Ibrahim’s comments here.

Update, 28 Nov 2013: If the process appears to work but doesn’t seem to make a difference, consider Tom’s comments below. Depending on your monitor an extra tweak may be required.

Update, 13 Nov 2013: Andrew comments below that he has modified the script to add some useful new features, and provides a link to his GitHub for those wishing to use it instead.

Update, 27 Oct 2013: If you’ve applied this fix before, the OS X Mavericks update will overwrite it. I’ve successfully re-applied the fix by following exactly the same steps, and other commenters below have done so, too.

895 thoughts on “Force RGB mode in Mac OS X to fix the picture quality of an external monitor

  1. I found that upgrading to El Capitan had wiped out my override on my ASUS PA279. It had also changed the background picture to something I used a year ago and killed my calibration! Of course I couldn’t copy the override folder anymore. So I rebooted into recovery mode, opened a terminal in recovery and manually copied the folder into the new overrides folder (System/Library/Displays/Contents/Resources/Overrides) . In recovery mode, the internal hard disk gets mounted into /Volumes/Macintosh HD/ so make sure you take that into account. I would guess that you can also do this using a single user boot (hold command-S during a boot).

  2. i tried to write ruby patch-edid.rb in terminal but give me an error.
    I anyhow copied the two file in the override folder but nothing happen.
    what shall i do?
    i have a macbook air brand new.

  3. Thank you for this amazing post. I’m glad to hear that I’m not the only one facing these issues. I tried your solution, and it created a file and folder, which I’ve added to the Overrides folder, but my monitor still appears blurry. The monitor is set to its max resolution of 1080 (I realize this is not terribly high), but the fonts are still blurry. Could it just be the monitor itself?

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  6. I followed all the steps and I think everything worked correctly. The script ran, It said “found display ‘SyncMaster’: vendorid 19501, productid 639, EDID:” and then I placed the folder in the Overrides folder. I checked the generated file for weird characters but found none. However, I’m not able to see any significant improvements.

    Computer : MBP Mid-2014, 15 retina.
    Monitor:Samsung 226bw

    Any ideas?

  7. Hi:
    I just bought this Screen ACER K272 HULA and i have the same issue.
    Connected DVI-DVI I have no issues but max. resolution is FHD, when i
    try to connect mDP – DP all i get is a No signal error… I have a Mac
    Pro mid 2010 with this wire

    I tried to force RGB but still with no luck and no signal income.
    I also tried to change DP setting but i have not any DP setting in my
    menu, so I cant do it.

    Please help.
    What can i do?

  8. Brilliant, thank you! This just fixed the problem on my LG 34UM95 with a new Macbook. I’m hoping I can get it working with my Dell U2412M at work as well!

  9. I just bought a new 3.0 GHz Dual-Core Intel Core i& mini mac and an ultrasharp 27″ dell U2713H monitor. I connected the computer to the monitor with a Mini-DisplayPort-to-DisplayPort Cable and get nothing but a “No DVI-D Cable. The display will go into Power Save Mode in 5 minutes” message. Can anyone help?!

  10. Restarting may be un-nessicary. In Yosmites 10.10.5 with a 2ndary HDMI monitor, instead of restarting I disconnected the Monitor’s HDMI cable and reconnected it and the Font quality improved drastically, though it is still not a clear as my built in display. Note sure if this makes any difference but I already had a /System/Library/Displays/Overrides/DisplayVendorID-… with the same number so I only copied in the resultant DisplayProductID-#### and left the other pre-existing DisplayProductID-#### files in place.

  11. Do twice exactly as your post and my Dell U2415 display shows “Display with forced RGB mode (EDID override)”, but the text on external monitor still blurry as before. So sad.

  12. Question: Have a DELL U2414H and an Apple Thunderbolt Monitor.

    I want to run both monitors at the same time. If I run the script, will it effect the Thunderbolt Monitor as well or just change the settings on the DELL U2414H monitor?

    I am using a mac mini 2012. I can use the extra Thunderbolt out on the monitor to daisy chain the monitors and the DELL looks ok, but would rather use the port instead for a thunderbolt hard drive. I would like to attach the DELL to the HDMI port of the mac mini and not have the OS X see it as a T.V. Anyone else try to do this? Will it work and not cause a problem with the thunderbolt monitor?

    Those with a mac mini 2012 question: also, I can use the thunderbolt hard drive to daisy chain the DELL monitor and get the system to see it as a monitor and not a T.V. But due to the lesser graphics card in the mac mini 2012 it works but system is pushing it. If I hook up the DELL instead to the HDMI port, does it lessen the work on the graphics card since the system was designed to have a secondary monitor or T.V. on the HDMI port instead of daisy chaining the Thunderbolt port to carry two monitors?

    Thanks and appreciate the help. I hope this method will make my second monitor look better!!!

  13. Ok guys, following the instructions. I am not seeing a new folder being created. Here is my setup. Early 2015 MBP Retina. Mini Display out to VGA to HP 23w Monitor. Help?

  14. My setup: Late 2015 Retina Macbook Pro. Dell P2715Q 4K. Dell U2414H. … The 27″ 4K is beautiful! The Retina Screen is beautiful! The 24″ blurry …. but I use that screen for VMWARE WIN8 and its crystal clear! So I ran across this site…. I ran the fix, the 24″ seems a tad better but something is still off. Using this 24 on my windows PC it shines but on the Mac it looks blah. Kind of disappointing but very happy to have found this site and realize I’m not alone with this issue.

  15. after upgrade 10.10.3 – 10.11 beta3 i have no 2560×1080 anymore on external monitor on my hackintosh.
    After ruby patch-edid.rb – i even have less options then before ( no 1080p 1080i)
    Looks like Aplleintelframebuffer azul patches (10.10-Azul-Port_0x6-DP2HDMI and 10.10-Azul-Port_0x7-DP2HDMI) do not work on 10.11 (

  16. i’m experiencing this issue on el capitan (it worked fine for me before i got on the el capitan beta). I don’t really want to mess with these scripts so im going to live with it and hope a subsequent beta release fixes this issue

  17. Thank you so very much for this! I have a Macbook Air 11 2015 and bought one of those Display to HDMI adapters. When I connected my Macbook Air to my Dell Ultrasharp monitor the text was so fuzzy I could barely read anything. After Googling around I found your site. I followed the steps and everything worked perfectly. For those still needing help: I had to go into Preferences on Finder to turn on the ability to access the Home folder (your Username).

  18. When I use my Nikon 9000 scanner I need one thunderbolt port on my mac book pro for it, the second is used for the display, a Hp 27x. But then I cannot use my main harddsik, a thunderbolt WD my passport pro. Tried first Hdmi for my Hp, but type was pixelated which gave me a headache, then a docking solution with the same result. Tried Hdmi to display port cable I had lying around, did not work either. Now tried this patch and yes the display is as good as it was attached to the display port! Thanks a lot and shame on Apple! As a late switcher from win to mac I was so far very satisfied with the switch (lesser problems with hardware and software) but this issue got on my nerves. There is really the danger that Apple is relying more on more on golden watches for rich people than on rock solid products for professionals.

  19. Sweet. Totally fixed me on Mac Mini to HP2309m HDMI to HDMI. Thank goodness there are still SOME people out there who know what they are doing.

  20. Method not working anymore on OS X 10.11 El Capitan. There’s no /S/L/Displays/Overrides/ folder anymore and nothing happens if even we place one. Any Ideas how to solve it?

  21. Hi Guys, Im on a Mac Book Pro running Mavericks 10.9.5. Im on a AOC monitor, through Mini Display Port. Ive just run the script and placed it into my display /file/ overide. After restarting, and looking in system pref /displays,/scaled, its showing display with forced RGB mode. Is this what people show? Is this correct?
    My font is still not crisp and has some blurriness so I’m thinking I might have done something wrong?
    Im also on 1920x 1080.

    • I have the same problem as Erik.
      It seems to work, I can see my monitor´s name and it has only regular letters and numbers.
      I just need and use 1920×1080, but it´s still blurry.

  22. Hi guys,

    I’m having the same blurry text rendering issue on my new NEC EA274WMi. Connected to windows machine it’s perfectly sharp. Connected to a macbook pro retina late 2012 OS X Yosemite all texts are blurry.

    I used the patch mentioned in this post but it doesn’t work. Once installed it forces me to use a lower resolution than the native 2560 x 1440, making everything more blurry.

    Already tried with hdmi/DVI/displayport cables, disabling the lcd font smoothing and reducing the transparency in System Preferences.

    Who can give me some suggestions?
    Thanks in advance.


  23. All I had to do with my external 1920×1080 Samsung and retina MBP 13″ was.. go through the display’s menus and find “screen fit” option from there. Blur gone.

  24. The short story: I now have my MacBook Pro running my new Acer K272HUL 27″ running at 2560×1440 pixels and it is sweet!

    The longer story: I have a Macbook Pro (Mid 2012 model) manufactured in 2015 (got it in an emergency for $800 its only a few months old and they are around $1,300 Australian Dollars and I bought an Acer K272HUL 27″ display to get me by until I get my new iMac Retina 27″ (I get it early June 2015 really can’t wait) as my iMac 27″ Mid 2009 27″ decided it would die a week or so before I was going to update anyway and I wanted to use the Macbook Pro with the Acer at full resolution 2560×1440 in the meantime, well tried everything all the hints tips suggestions I called a local Apple dealer and called Apple support who put me on to this site.

    The solution was as follows:

    First be fore you try anything you need one of these its called a Mini-DisplayPort-to-DisplayPort Cable

    I tried a Mini-DisplayPort-to-DVI and a Mini-DisplayPort-to-HDMI
    They both only gave me 1920×1080 resolution which is not right.

    You will only get this wroking correctly if you get the Mini-DisplayPort-to-DisplayPort Cable

    You have to use the Mini-DisplayPort-to-DisplayPort Cable they should only cost you around $10-$20 Australian dollars mine is 2mtrs and cost me $9.00 Australian dollars

    How to force RGB in Mac OS X
    1. Download the patch-edid.rb script here: and extract it in to your home directory, If you don’t know where your home folder is use these instructions: In your home folder, there are folders for your desktop files, downloads, pictures, documents, movies, music, and for any public files. To open your Home folder, click the desktop to make sure you’re in the Finder, then choose Go > Home.

    2.Connect only the external monitor(s) in question (I closed my MacBook lid, for example). The script will make override files for any connected monitor.

    3. Type “ruby patch-edid.rb” in Terminal.

    4. A new folder will be created in your home directory. Move it into the “/System/Library/Displays/Overrides” folder. If finder tells you that you are overwriting an existing folder, consider backing it up first.
    Restart your computer, enjoy your monitor.

    To undo the changes, either delete the folder you had copied to the Overrides folder (if it didn’t already exist) or replace it with the folder you had backed up.

    Hope this helps some people as I wasted more than 7 hours on this issue before I resolved it.

    You have to use the Mini-DisplayPort-to-DisplayPort Cable they should only cost you around $10-$20 Australian dollars mine is 2mtrs and cost me $9.00 Australian dollars

  25. Worked beautifuly for me. I have a Dell U2715H via display port to mini display port cable to a 2010 aluminum Mac Pro. On OS X 10.8.5. before the script everything looked great except for text which was a little fuzzy and gave me headaches. Also i realized on system profilethat the monitor was detected as Television. Wfter the script the text looks great, i have no headaches and the monitor isn’t recognized as a Television on the system profile.
    Thank you!!
    Btw. if on system profile it says Television:yes i think you have to run the script.

  26. Thanks! Worked like a charm on rMBP 13″ Early 2015 (running Yosemite 10.10.3) connected to HP 2310m via HDMI cable.

  27. Hi Mathew,

    I came today with my new laptop home and was loosing my mind over this problem. Now works like a charm with Andrew’s script. I’m so very grateful to both of you.

  28. Hi, thought i’d post this as it may help some:
    I’ve been using an ASUS Pro Art PA279Q monitor for 12 months with my MBP 15″ mid 2012 running more recently 10.9.3 yosemite connected via daisy chained thunderbolt drives (imac->promise pegasus R4->WD mybook thunderbolt duo->display) with display at end. crisp fonts and colours great, never needed tweaking. MBP logic board died so bought a refurbished imac 27″ 2013 and setup from MBP time machine backup. when PA279Q was plugged directly into imac thunderbolt port (using mini display port-VGA adapter same as before) it gave me shitty resolution (1280×800 or less) with fuzzy fonts.
    rerouting the display through the HDD daisy chain restored previous display settings for external monitor giving me 1920×1080 and crisp fonts as well as a PA-248 colour profile to work with. I’ve no idea why but perhaps this may be useful to others experiencing similar issues. i was about to try the force RGB suggestions of the past 2 years of threads but this solved my issue.

  29. Hi,

    I tried what you wrote but it didn’t work for me…
    I’m using a Macbook Pro from 2012 with Yosemite. When i connect with HDMI my laptop with my screen (HP 2311x), my Macbook see the screen (it recognizes it) but the inverse is not true…

    Thanks a lot for your help, i’m a little deperate ^^”

  30. Oh cool someone from the apple forums helped me, this worked:

    Choose Go to Folder from the Finder’s Go menu and paste /System/Library/Displays/Overrides into the dialog box.

    The trick seems to have worked, though I can’t tell if the quality is still a little off, or if it’s just hard swapping between retina and non-retina? I’ve got a headache and I can’t tell if it’s because of this…

  31. Hey there, new Mac user here. I can’t seem to find the /System/Library/Displays/Overrides folder. Anyone know where it is? I was able to unhide the Librarys folder, but there’s no folder called Displays in there.

  32. Just when I was giving up with my monitor (AOC 2560×1080) I found this post. I have no word to tell you how grateful I am. I am in the nice-text-and-beautiful-colors world again!

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